On Mon, 7 Oct 2024 at 17:35, Mukesh Ojha <quic_mojha@xxxxxxxxxxx> wrote:
>
> On Sun, Oct 06, 2024 at 10:38:01PM +0300, Dmitry Baryshkov wrote:
> > On Sat, Oct 05, 2024 at 02:53:54AM GMT, Mukesh Ojha wrote:
> > > From: Shiraz Hashim <quic_shashim@xxxxxxxxxxx>
> > >
> > > Qualcomm’s PAS implementation for remote processors only supports a
> > > single stage of IOMMU translation and is presently managed by the
> > > Qualcomm EL2 hypervisor (QHEE) if it is present. In the absence of QHEE,
> > > such as with a KVM hypervisor, IOMMU translations need to be set up by
> > > the KVM host. Remoteproc needs carveout memory region and its resource
> > > (device memory) permissions to be set before it comes up, and this
> > > information is presently available statically with QHEE.
> > >
> > > In the absence of QHEE, the boot firmware needs to overlay this
> > > information based on SoCs running with either QHEE or a KVM hypervisor
> > > (CPUs booted in EL2).
> > >
> > > The qcom,devmem property provides IOMMU devmem translation information
> > > intended for non-QHEE based systems.
> > >
> > > Signed-off-by: Shiraz Hashim <quic_shashim@xxxxxxxxxxx>
> > > Co-Developed-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> > > Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> > > ---
> > > .../bindings/remoteproc/qcom,pas-common.yaml | 42 +++++++++++++++++++
> > > .../bindings/remoteproc/qcom,sa8775p-pas.yaml | 20 +++++++++
> > > 2 files changed, 62 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/remoteproc/qcom,pas-common.yaml b/Documentation/devicetree/bindings/remoteproc/qcom,pas-common.yaml
> > > index 63a82e7a8bf8..068e177ad934 100644
> > > --- a/Documentation/devicetree/bindings/remoteproc/qcom,pas-common.yaml
> > > +++ b/Documentation/devicetree/bindings/remoteproc/qcom,pas-common.yaml
> > > @@ -52,6 +52,48 @@ properties:
> > > minItems: 1
> > > maxItems: 3
> > >
> > > + iommus:
> > > + maxItems: 1
> > > +
> > > + qcom,devmem:
> > > + $ref: /schemas/types.yaml#/definitions/uint32-matrix
> > > + description:
> > > + Qualcomm’s PAS implementation for remote processors only supports a
> > > + single stage of IOMMU translation and is presently managed by the
> > > + Qualcomm EL2 hypervisor (QHEE) if it is present. In the absence of QHEE,
> > > + such as with a KVM hypervisor, IOMMU translations need to be set up by
> > > + the KVM host. Remoteproc might need some device resources and related
> > > + access permissions to be set before it comes up, and this information is
> > > + presently available statically with QHEE.
> > > +
> > > + In the absence of QHEE, the boot firmware needs to overlay this
> > > + information based on SoCs running with either QHEE or a KVM hypervisor
> > > + (CPUs booted in EL2).
> > > +
> > > + The qcom,devmem property provides IOMMU devmem translation information
> > > + intended for non-QHEE based systems. It is an array of u32 values
> > > + describing the device memory regions for which IOMMU translations need to
> > > + be set up before bringing up Remoteproc. This array consists of 4-tuples
> > > + defining the device address, physical address, size, and attribute flags
> > > + with which it has to be mapped.
> >
> > I'd expect that this kind of information is hardware-dependent. As such
> > it can go to the driver itself, rather than the device tree. The driver
> > can use compatible string to select the correct table.
> >
>
> IIUC, are you saying that to move this into driver file and override the
> compatible string via overlay ?
Ideally we should live without compat overrides. On the other hand,
sc7180 and sc7280 provide an example of doing exactly that.
>
> > > +
> > > + remoteproc@3000000 {
> > > + ...
> > > +
> > > + qcom,devmem = <0x82000 0x82000 0x2000 0x3>,
> > > + <0x92000 0x92000 0x1000 0x1>;
> > > + }
> > > +
> > > + items:
> > > + items:
> > > + - description: device address
> > > + - description: physical address
> > > + - description: size of mapping
> > > + - description: |
> > > + iommu attributes - IOMMU_READ, IOMMU_WRITE, IOMMU_CACHE, IOMMU_NOEXEC, IOMMU_MMIO
> > > + enum: [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
> > > + 25, 26, 27, 28, 29, 30, 31 ]
> >
> > Attributes should definitely be defined and then the DT should use
> > defines rather than the raw values.
> >
>
> Ack.
>
> -Mukesh
>
--
With best wishes
Dmitry
